How to draw grease pencil on a surface (blender 2,75)?
Add a new Grease Pencil datablock in a properies window (N). In Tool Shelf (T) change the stroke placement to Surface. Hold  D and then press and hold the LMB button to draw. Disable the X Ray option if you don't want to see the strokes through the object. To erase, hold  D button and then press and hold the RMB.